The present disclosure relates to antenna devices. Japanese Unexamined Patent Application Publication No. 2010-161612 discloses a directivity-variable antenna device capable of changing the directivity even in the case of being surrounded by a metal housing. Part of the metal housing of a wireless communication apparatus is cut out, and the antenna device including a variable directivity antenna and a plurality of waveguides is mounted in the cutout section. The stated antenna device includes the waveguides having mutually different opening widths, a waveguide connection portion connecting the waveguides at one ends thereof, and the variable directivity antenna provided in the waveguide connection portion. Radio waves are propagated to one of the two waveguides by switching the directivity of the variable directivity antenna.
In Japanese Unexamined Patent Application Publication No. 2010-161612, an example in which the antenna device including the waveguides is mounted inside the metal housing of the stationary-type apparatus is described. However, because circuit components are mounted in high density inside a metal housing of a mobile terminal such as a smart phone or the like, it is difficult to mount an antenna device including a waveguide inside the metal housing. In particular, it is difficult to mount a waveguide so that radio waves are guided in a thickness direction of a thinned metal housing.
Further, it is difficult in some case to provide a large cavity in a metal housing so as to radiate radio waves from the standpoint of design or strength.